WorksheetsAnti-Lock Braking System (ABS) Fundamentals
Total questions: 20
Worksheet time: 10mins
How are ABS configuration names determined, according to the configuration overview?
By the number of brake cylinders and calipers
By the number of modulator valves and sensors on the vehicle
By the number of axles and wheels
By the vehicle’s gross weight rating
Which statement best distinguishes an open-circuit wheel speed sensor fault from a healthy sensor when checked with an ohmmeter?
Open circuit shows a high or infinite resistance; healthy sensor reads around 1 kΩ
Open circuit shows about 1 kΩ; healthy sensor reads near 0 Ω
Open circuit shows fluctuating mid-range resistance; healthy sensor shows infinite resistance
Open circuit cannot be detected with resistance testing
Why are short reaction times emphasized for the ABS solenoid valve system?
To achieve high control performance while minimizing air consumption for ABS-controlled braking and ASR operation
To reduce brake pad wear by eliminating heat
To improve dashboard indicator brightness
To increase fuel economy through regenerative braking
Given the described design, which component does NOT directly change due to the solenoid action?
The main brake chamber volume
The control chambers of the diaphragms
The flow through the exhaust port
The feed from double check valves
A diagnostic test shows sluggish pressure modulation. Based on the text, which deficiency would most directly explain poor ABS performance?
Long reaction times in the solenoid valve actuation
Excessive brightness of the ABS indicator lamp
High voltage at the battery terminals
Low tire tread depth
Which ABS phase would be responsible for restoring braking force after slip has been reduced?
Pressure increase phase
Pressure decrease phase
Electrical diagnostic phase
Self-bleeding phase
A vehicle exhibits effective traction control (ASR) but inconsistent ABS performance. Which shared component characteristic should be examined based on the text?
Solenoid valve reaction time and control of diaphragm chambers
Tire inflation procedure
Alternator belt tension
Wiper motor current draw
What is the functional result when the supply diaphragm valve closes in the hold phase?
Port 2 is separated from port 1 preventing further pressure increase
Brake chamber is vented to atmosphere
Exhaust port 3 is locked open increasing pressure
Control chamber 4 is isolated causing pressure rise
Which action prevents any further pressure increase in the brake cylinder during the hold phase?
Separation of port 2 from port 1 by the closed supply diaphragm
Opening of exhaust port 3 to atmosphere
Lifting exhaust diaphragm 7 to vent pressure
Closing control chamber 4 to atmosphere
Which statement best describes differential braking?
Applying different amounts of braking torque to individual wheels to improve control
Locking all wheels equally to maintain straight-line braking
Reducing brake temperature through forced air cooling
Automatically engaging four-wheel drive at low speeds
Which statement correctly contrasts ASR actions based on road conditions?
ASR may start engine control, brake control, or both when excessive slip is detected
ASR always applies full braking regardless of surface
ASR only reduces engine torque on gravel surfaces
ASR only functions above highway speeds
Protecting the transmission and tyres is listed as a benefit of which system?
ASR
ESP only
TPMS only
EBS only
What does the double check valve ensure when both the driver brakes and ASR intervenes?
Whichever source has pressure (driver or ASR feed) can apply the brakes without conflict
Both sources are blocked to prevent over-braking
Only the driver's input is allowed through, disabling ASR
Only ASR input is allowed through, disabling the driver
Which statement is accurate about the presence of ASR and ABS units during differential braking?
ASR acts alone without ABS involvement
The ABS system’s pressure modulating valve controls pressure rise coordinated with the ASR electro-valve
ABS disables ASR to avoid conflicting commands
Only mechanical differentials are used; no valves are involved
Which speed-related behavior is specifically stated for the differential brake function?
It is only active above highway speeds
It switches off automatically above about 30 km/h unless already working
It increases linearly with vehicle speed
It is disabled below 10 km/h to prevent wheel lock
Which element serves as the interface between driver brake demand and system hydraulic circuits before ABS modulation?
Brake valve (4)
Rear brake modulator (6)
Differential electrovalve (8)
ASR Off road switch (13)
Which lamp behavior confirms activation of ASR traction mode to warn the driver?
ABS lamp steady on
ASR lamp fast flashing
ASR lamp slow flashing
No lamp indication is provided
What does the overview imply about EBS and trailers?
EBS coordinates braking between a towing vehicle and its trailer
EBS disconnects trailer brakes to prevent skidding
EBS requires trailers to have no independent brakes
EBS only functions without a trailer attached
Which statement best aligns with EBS’s role in fleet competitiveness?
EBS helps fleets meet higher braking performance expectations driven by market competition
EBS primarily functions as a navigation aid to reduce route times
EBS increases axle loads beyond legal limits
EBS eliminates the need for driver training
In a combination vehicle, how does EBS contribute to coordinated braking?
By balancing braking forces across the towing vehicle and its trailer on an ongoing basis
By applying brakes to the trailer only during parking
By isolating the trailer from the towing vehicle’s brake control
By engaging only the engine retarder on descents
